Dr. Hal Herzog, as part of his column, "Animals and Us" in Psychology Today, surveys the current literature on animal-assisted therapy and identifies a number of weaknesses in the existing literature, including a lack of a non-treatment control group, insufficient numbers of subjects, no controls for effects of novel experiences, no written manual spelling out the treatment procedures (important for standardization and replication), no use of “blind observations” to control for unconscious bias on the part of the researchers, reliance on self-reports rather than objective measures, lack of long-term follow-up studies, and putting a positive spin on negative results. In concluding the article, Dr. Herzog writes that it is still not clear how important the animal is in animal-assisted therapy.